<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
/*
    //1. if
    var count = 3;
    if (count == 3) {
        alert(count);
    }*/

/*

    //2. switch
    var num = 3;
    switch (num) {
        case 1: {
            alert("星期一");
            break;
        }

        case 2: {
            alert("星期二");
            break;
        }

        case 3: {
            alert("星期三");
            break;
        }

        case 4: {
            alert("星期四");
            break;
        }

        case 5: {
            alert("星期五");
            break;
        }

        case 6: {
            alert("星期六");
            break;
        }

        case 7: {
            alert("星期日");
            break;
        }


        default: {
            alert("输入的星期有误");
            break;
        }
    }
*/


    // 3. for
/*

    var sum = 0;
    for (let i = 1; i <= 100; i++) {
        sum += i;
    }
    alert(sum);
*/

/*
    // 4. while

    var sum = 0;
    var i = 1;
    while (i <= 100) {
        sum += i;
        i++;
    }
    alert(sum);*/


    // 5. do...while

    var sum = 0;
    var i = 1;
    do {
        sum += i;
        i++;
    }
    while (i <= 100);
    alert(sum);


</script>
</body>
</html>